One of the most splendid achievements of the Byzantine emperors was the preservation of Roman law for the medieval and modern worlds. Roman law had developed from many sources. By the fourth century, it had become a huge, bewildering mass, and its sheer bulk made it almost unusable.

Sweeping and systematic codification took place under the emperor Justinian. He appointed a committee of eminent jurists to sort through and organize the laws. The result was the Corpus Juris Civilis (KAWR-puhs JOOR-uhs sih-VIH-luhs) (Body of Civil Law), a multipart collection of laws and legal commentary issued from 529 to 534. The first part of this work, the Codex, brought together all the existing imperial laws into a coherent whole, eliminated outmoded laws and contradictions, and clarified the law itself. It began with laws ordering the interpretation of Christian doctrine favored by the emperor, and affirming the power of the emperor in matters of religion. The rest of the Codex was structured by topic and included provisions on every aspect of life, including economic issues, social concerns, and family life.

The second part of Justinian’s compilation, the Digest, is a collection of the opinions of foremost Roman jurists on complex legal problems, and the third part, the Institutes, is a handbook of civil law designed for students and beginning jurists. All three parts were given the force of law and formed the backbone of Byzantine jurisprudence from that point on. The Corpus Juris Civilis was lost in western Europe with the end of the Roman Empire, but it was rediscovered in the eleventh century and came to form the foundation of law for nearly every modern European nation.